Animals in both agricultural and research settings are often marked for management and control. Prior art methods for identifying small research animals include attaching metal ear tags and employing implanted or ingested electronic tags. Prior art metal ear tags are associated with host animal tissue reaction, tissue irritation, cancer incidence, other host animal health degradation and/or deformation of the host animal ear due to relatively high weight of the metal ear tag. In addition, prior art metal ear tags can induce host animal efforts to dislodge the ear tag that can result in damage to the animal itself and/or the ear tag.
The prior art includes transponder tags with radio frequency identification devices, or “RFID”. Reading a radio frequency identification device requires the use of an RFID reader, i.e. an electronic device that communicates through wireless transmission with the RFID device. The RFID tag, passively responsive to an excitation signal transmitted from the RFID reader, can communicate coded information from the RFID transponder tag to the RFID reader, which then receives and decodes the information. Prior art implanted or ingested electronic tags are limited by their need to reflect or transmit a stream of data (e.g. their unique identification numbers) to the outside world. This requires relatively expensive transponder and receiver hardware and an invasive and risky surgical implantation process. Additionally, due to an inability to differentiate the identification number signal from two or more adjacent animals with passive RFID tags, animals must be first separated from one another or removed from the cage prior to scanning the animal. Animals which are group housed may not be scanned while within the cage because there is no way to direct the scanning area of the reader and identify a specific animal with certainty. It is preferable to scan group-housed animals without first removing them from their cage.
While animals are currently tagged with radio frequency identification devices in the prior art, it is often preferable that individual identification of a specific animal could be easily distinguished by a technician or laborer without the use of electronic or optical equipment. In addition, particularly when the animals of interest have modestly sized ears, such as mice bred for scientific research, it is preferable that a tag attached to an animal be of minimal discomfort or irritation to the host animal. It is also preferable for identifying markings to be readily visible, observable, or accessible, yet also verifiable or certifiable.
There is therefore an unmet need to provide a device and method that enables a reliable visual distinction of an animal by a laboratory researcher or animal caretaker.